I will offer the early morning play & read "shift" thus allowing DC and to sleep in when the DGc are under 10yo.
I'll buy books etc and make play dough, bake, do messy play. And not sit in my chair and ask when they are due to sleep or go to bed all the time.
I'll be me but older, and not come to life with wine once they go to bed.
I'll offer to go on holiday with them or them with us (with or without the DC) because I mean it and not use them as an excuse to be snide about the world. E.g. if my DIL or SIL has a heritage from another part of the world I will go and learn about their culture to appreciate the family, and not go there to look for poverty or find grounds for my prejudice.
I won't just see a Colour in my DGc, I'll see people, a future president, future astronaut, future componist, noble physics winner etc. I'll have hopes and dreams for my descendants, and not lament their diversity.
I'll roll around on the carpet and play trains/farms/zoos whatever if the DGC are all boys (like my mum does) and not keep giving pink tops/jogging bottoms as gifts lamenting the absence of a girl (a la MIL).
I'll learn to express an interest in their interests and not moan that my DS were gentler in their disposition.